U.S. patent number 9,007,213 [Application Number 12/297,489] was granted by the patent office on 2015-04-14 for methods and systems for object identification and for authentication.
This patent grant is currently assigned to Cornell University, The United States of America as represented by the Secretary of the Navy. The grantee listed for this patent is Keith L. Aubin, Jeffrey W. Baldwin, Harold G. Craighead, Brian H. Houston, Jeevak M. Parpia, Robert B. Reichenbach, Maxim Zalalutdinov. Invention is credited to Keith L. Aubin, Jeffrey W. Baldwin, Harold G. Craighead, Brian H. Houston, Jeevak M. Parpia, Robert B. Reichenbach, Maxim Zalalutdinov.
United States Patent |
9,007,213 |
Aubin , et al. |
April 14, 2015 |
**Please see images for:
( Certificate of Correction ) ** |
Methods and systems for object identification and for
authentication
Abstract
Methods and systems for object identification and/or
authentication.
Inventors: |
Aubin; Keith L. (Ithaca,
NY), Baldwin; Jeffrey W. (Alexandria, VA), Craighead;
Harold G. (Ithaca, NY), Houston; Brian H. (Fairfax,
VA), Parpia; Jeevak M. (Ithaca, NY), Reichenbach; Robert
B. (Portland, OR), Zalalutdinov; Maxim (Silver Springs,
MD) |
Applicant: |
Name |
City |
State |
Country |
Type |
Aubin; Keith L.
Baldwin; Jeffrey W.
Craighead; Harold G.
Houston; Brian H.
Parpia; Jeevak M.
Reichenbach; Robert B.
Zalalutdinov; Maxim |
Ithaca
Alexandria
Ithaca
Fairfax
Ithaca
Portland
Silver Springs |
NY
VA
NY
VA
NY
OR
MD |
US
US
US
US
US
US
US |
|
|
Assignee: |
The United States of America as
represented by the Secretary of the Navy (Washington, DC)
Cornell University (Ithaca, NY)
|
Family
ID: |
38834184 |
Appl.
No.: |
12/297,489 |
Filed: |
April 19, 2007 |
PCT
Filed: |
April 19, 2007 |
PCT No.: |
PCT/US2007/066940 |
371(c)(1),(2),(4) Date: |
April 07, 2009 |
PCT
Pub. No.: |
WO2007/149621 |
PCT
Pub. Date: |
December 27, 2007 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20090206987 A1 |
Aug 20, 2009 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
60793334 |
Apr 19, 2006 |
|
|
|
|
Current U.S.
Class: |
340/572.1;
340/10.1; 340/10.4 |
Current CPC
Class: |
G06K
19/0672 (20130101); G06K 7/10336 (20130101); G06K
19/0723 (20130101) |
Current International
Class: |
G08B
13/14 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
WO 0167413 |
|
Sep 2001 |
|
WO |
|
WO 2004084131 |
|
Sep 2004 |
|
WO |
|
WO 2005020434 |
|
Mar 2005 |
|
WO |
|
WO 2005020434 |
|
Mar 2005 |
|
WO |
|
Other References
Zalalutdinov, M. et al. Shell-type micromechanical actuator and
resonator. Applied Physics Letters. vol. 83 No. 18. Nov. 3, 2003.
cited by applicant .
International Search Report for PCT/US07/66940 dated Feb. 26, 2008.
cited by applicant .
U.S. Appl. No. 60/793,334, filed Apr. 19, 2006, Resonant Spectrum
Identification. cited by applicant.
|
Primary Examiner: Backer; Firmin
Assistant Examiner: Wilson; Brian
Attorney, Agent or Firm: Burns & Levinson LLP Lopez;
Orlando
Government Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
The U.S. Government has certain rights in the invention.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a U.S. national stage application under 35
U.S.C. 371 of International Application No. PCT/US07/66940 filed
Apr. 19, 2007 and entitled METHODS AND SYSTEMS FOR OBJECT
IDENTIFICATION AND FOR AUTHENTICATION, which in turn claims
priority of U.S. Provisional Patent Application Ser. No.
60/793,334, entitled "Resonant Spectrum Identification," filed on
Apr. 19, 2006, which is incorporated by reference herein.
Claims
What is claimed is:
1. A method for using imperfections induced by fabrication
variations for identification/authentication of an object, the
method comprising the steps of: connectively positioning a
micromechanical resonator structure with respect to the object, the
micromechanical resonator structure having a substantially unique
characteristic signal; the substantially unique characteristic
signal being produced by induced motion of the micromechanical
resonator structure; uniqueness of the substantially unique
characteristic signal resulting from the imperfections induced by
the fabrication variations; exciting motion of the micromechanical
resonator structure to induce an excitation response signal; said
excitation response signal comprising a vibration spectrum, a
spectrum of the induced motion, phase as a function of frequency
for the induced motion and phase of response with respect to a
detection subsystem; detecting features of the excitation response
signal; and comparing the features of the excitation response
signal to a stored substantially unique characteristic signal; the
stored substantially unique characteristic signal being obtained by
exciting motion of the micromechanical resonator structure to
induce the substantially unique characteristic signal, detecting
features of the substantially unique characteristic signal and
storing the detected features as the stored substantially unique
characteristic signal; the stored substantially unique
characteristic signal uniquely identifying the object within a
class of objects; the stored substantially unique characteristic
signal being such that regeneration or reassignment of the stored
substantially unique characteristic signal to another object within
the class is highly unlikely or effectively impossible; whereby the
object is identified/authenticated.
2. The method of claim 1 further comprising the step of
communicating an indication of a result of the comparison.
3. The method of claim 1 wherein the step of exciting motion of the
micromechanical resonator structure comprises inducing thermal
stresses in the micromechanical resonator structure.
4. The method of claim 1 wherein the step of exciting motion of the
micromechanical resonator structure comprises electromagnetically
exciting the micromechanical resonator structure.
5. The method of claim 1 wherein the step of exciting motion of the
micromechanical resonator structure comprises inducing stresses in
the micromechanical resonator structure.
6. The method of claim 1 wherein the step of exciting motion of the
micromechanical resonator structure comprises coupling motion from
another structure.
7. The method of claim 1 wherein the step of exciting motion of the
micromechanical resonator structure comprises acoustically exciting
the micromechanical resonator structure.
8. The method of claim 1 wherein the step of detecting the features
of the excitation response signal comprises optically detecting the
features of the excitation response signal.
9. The method of claim 1 wherein the step of detecting the features
of the excitation response signal comprises electromagnetically
detecting the features of the excitation response signal.
10. The method of claim 1 wherein the step of detecting the
features of the excitation response signal comprises detecting a
vibration spectrum of the excitation response signal.
11. A method for using imperfections induced by fabrication
variations for identification/authentication of an object, the
method comprising the steps of: positioning a micromechanical
resonator on a substrate, the micromechanical resonator having a
substantially unique excitation response signal; uniqueness of the
substantially unique excitation response signal resulting from the
imperfections induced by the fabrication variations; said
substantially unique excitation response signal uniquely
identifying the object within a class of objects; said
substantially unique excitation response signal being such that
regeneration or reassignment of said substantially unique
excitation response signal to another object within the class is
highly unlikely or effectively impossible; said substantially
unique excitation response signal produced by induced motion of the
micromechanical resonator; said substantially unique excitation
response signal comprising features a vibration spectrum, a
spectrum of the induced motion, phase as a function of frequency
for the induced motion and phase of response with respect to a
detection subsystem; exciting the micromechanical resonator to
induce said substantially unique excitation response signal;
detecting features of said substantially unique excitation response
signal; and storing the detected features as a stored substantially
unique excitation response signal, wherein said substantially
unique excitation response signal is compared with said stored
substantially unique excitation response signal for
identification/authentication of the object.
12. The method of claim 11, further comprising affixing the
substrate to the object.
13. A method for using imperfections induced by fabrication
variations for identification of an object, the method comprising
the steps of: exciting motion of a micromechanical resonator
structure, the micromechanical resonator structure having a
substantially unique characteristic signal, the micromechanical
resonator structure connectively positioned with respect to the
object; said substantially unique characteristic signal being
produced by excited motion of the micromechanical resonator
structure; said excited motion of the micromechanical resonator
structure inducing the substantially unique characteristic signal
which is thereafter stored as a substantially unique previously
determined characteristic signal; the substantially unique
characteristic signal comprising a vibration spectrum, a spectrum
of the excited motion, phase as a function of frequency for the
excited motion and phase of response with respect to a detection
subsystem; uniqueness of the substantially unique characteristic
signal resulting from the imperfections induced by the fabrication
variations; said substantially unique characteristic signal
uniquely identifying the object within a class of objects; said
substantially unique characteristic signal being such that
regeneration or reassignment of said substantially unique
characteristic signal to another object within the class is highly
unlikely or effectively impossible; detecting a characteristic
signal resulting from the excited motion of the micromechanical
resonator structure; comparing the detected characteristic signal
to the substantially unique previously determined characteristic
signal; and identifying the object in response to the
comparison.
14. The method of claim 13, further comprising, communicating a
signal comprising the identification of the object.
15. A method for using imperfections induced by fabrication
variations for identification of an object, the method comprising
the steps of: connectively positioning a micromechanical resonator
structure with respect to the object, the micromechanical resonator
structure having a substantially unique previously determined
characteristic signal; uniqueness of the substantially unique
previously determined characteristic signal resulting from the
imperfections induced by the fabrication variations; the
substantially unique previously determined characteristic signal
being produced by exciting motion of the micromechanical resonator
structure to induce a specific excitation response signal, said
specific excitation response signal produced by excited motion of
the micromechanical resonator structure; said specific excitation
response signal comprising a vibration spectrum, a spectrum of the
induced motion, phase as a function of frequency for the induced
motion and phase of response with respect to a detection subsystem;
detecting features of the specific excitation response signal and
storing the detected features as the substantially unique
previously determined characteristic signal; said substantially
unique characteristic signal uniquely identifying the object within
a class of objects; said substantially unique previously determined
characteristic signal being such that regeneration or reassignment
of the substantially unique characteristic signal to another object
within the class is highly unlikely or effectively impossible;
uniqueness of the substantially unique characteristic signal
resulting from the imperfections induced by the fabrication
variations; exciting motion of the micromechanical resonator
structure; detecting a characteristic signal resulting from the
excited motion of the micromechanical resonator structure;
comparing the detected characteristic signal to the substantially
unique previously determined characteristic signal; and
communicating an indication of the result of the comparison.
Description
BACKGROUND
This invention relates generally to authentication and
identification of objects, where identification in this context is
used to mean recognizing to an acceptable degree of confidence an
instance of an object. Objects may be any sort of object, and may
themselves be associated with items, goods, people, animals,
materials, and so on.
In security systems, there are many candidate identification
technologies, including biometric technologies such as
fingerprints, retinal scans, iris scans, and facial recognition
algorithms. Biometric identification information is used to verify
a unique identity.
One example of a conventional technology utilized to identify
objects is Radio Frequency Identification (RFID) technology. With
conventional Radio Frequency Identification (REID) technologies, an
interrogator containing a transmitter generates an electromagnetic
field through which an electronic tag containing a receiving
antenna may pass. The electromagnetic field energizes the circuitry
on the tag, which then transmits an identification number or code.
Other functionality, such as data storage, or computation, also may
be implemented on the tag.
Such technology may be used to identify objects, because,
typically, an identification number communicated by the tag when it
is energized is selected to be substantially unique, at least
within the particular domain, and so the transmitted identification
number may serve to identify the goods or people with which an
object containing the tag is associated.
Such technology also may be used to authenticate (i.e., to verify)
the identity of a person, animal, or thing associated with a tag,
within a desired degree of confidence, if the tag is treated as
evidence of the identity of such person, animal, or thing.
Generally speaking, RFID technology is useful for authentication
only to the extent that it is difficult for a would-be forger or
impersonator to replicate the behavior of a given tag, by
manufacturing a duplicate tag, or otherwise. In many cases, the
design of RFID tags is well known, and the technology is such that
they may be duplicated. Some RFID tags exist that have encryption
or other cryptographic functionality, but such tags are expensive,
and the processing power on the tags is limited. As a result, it
may not be feasible or cost-effective to maintain the security of a
conventional RFID identification system against a determined
attacker.
BRIEF SUMMARY
In one instance, an embodiment of the method of for identification
and/or authentication of objects and/or materials includes
connectively positioning a micromechanical resonator structure with
respect to an object, the micromechanical resonator structure
having a substantially unique predetermined characteristic signal,
exciting motion of the micromechanical resonator structure,
detecting a characteristic signal of the excited motion and
comparing the detected characteristic signal to the substantially
unique predetermined characteristic signal. The object/material can
be identified/authenticated as a result of the comparison.
In another aspect, an identification medium (e.g., a card, tag,
token, document, and so forth) includes identification information
for a person. The identification information may be stored
electronically, magnetically, and so forth (e.g., in a memory,
disk, or on magnetic tape) and/or printed or otherwise visible on
the medium. The identification information, as non-limiting
examples, may include photographic information, biographic
information, biometric information, descriptive information,
demographic information, membership information, financial
information, and so forth. The identification medium also includes
a substrate, the substrate including a micromechanical resonator
structure, the micromechanical resonator structure including one or
more micromechanical resonators that each emit a characteristic
signal in response to an excitation signal.
In one instance, the authenticity of the identification medium may
be verified by exciting the micromechanical resonator structure and
verifying that the characteristic signal is similar to an expected
characteristic signal. The identification medium may also include a
communications medium for communicating the excitation signal to
the micromechanical resonator structures and other features. The
micromechanical resonator structure may communicate wirelessly
and/or over a wired communication medium with a reader.
In another aspect, an identification system includes a number of
substrates connectively positioned with respect to an object. Each
substrate includes a micromechanical resonator structure, the
micromechanical resonator structure including one or more
micromechanical resonators. The identification also includes a data
store, the data store storing a number of stored characteristic
signals. Each substrate has an associated respective stored
characteristic signal. Each stored characteristic signal is
recognizably distinct from the other stored characteristic signals.
Each stored characteristic signal is suitable for comparison with a
response of one of a micromechanical resonator structure to an
excitation signal.
In one embodiment, the system of these teachings also may include
an analysis subsystem for comparing the response of one of the
micromechanical resonator structures to an excitation signal. The
system also may include a number of objects, wherein each of the
plurality of substrates is connectively positioned to a respective
one of the substrates.
In another aspect, a method for manufacturing an identification
medium includes constructing on a substrate a micromechanical
resonator structure, the micromechanical resonator structure
including one or more micromechanical resonators. The method
includes connectively positioning the substrate with respect to an
object. The method includes exciting the micromechanical resonator
structure with an excitation signal, and receiving a response
characteristic signal of the micromechanical resonator structure,
the characteristic signal comprising a response of each of the
micromechanical resonators to the excitation signal. The method
includes storing the received responsive characteristic signal as
an expected response of the device for later comparison.
In some embodiments, the micromechanical resonators are constructed
such that fabrication variations detectably effect the
characteristic signal. In some embodiments, the stored
characteristic signal includes values derived from the
characteristic signal. In some embodiments, the stored
characteristic signal includes a frequency spectrum of the
characteristic signal. In some embodiments, the method also
includes delivering to a customer the object (with the connectively
positioned substrate) and the stored characteristic signal.
In another aspect, a computer readable medium includes a number of
stored characteristic signals, each stored characteristic signal is
associated with a respective micromechanical resonator structure.
Each stored characteristic signal is recognizably distinct from the
other of the plurality of stored characteristic signals. Each
stored characteristic signal is suitable for comparison with a
response of a micromechanical resonator structure to an excitation
signal. Each of the stored characteristic signals for comparison
with a response of a micromechanical resonator structure to an
excitation signal.
In another aspect, a method for identification includes
transmitting an excitation signal to an object. The object includes
a micromechanical resonator structure, which itself includes one or
more micromechanical resonator devices. The method includes
receiving a characteristic signal in response to the transmitted
excitation signal. The received characteristic signal may include a
combined response of each of the micromechanical resonators in the
micromechanical resonator structure to the excitation signal. The
method includes transmitting a signal confirming the identity of
the object if the received characteristic signal is sufficiently
similar to a stored characteristic signal associated with the
object.
Other embodiments of the method of these teachings and embodiments
of the system of these teachings are disclosed hereinbelow.
For a better understanding of the present teachings, together with
other and further needs thereof, reference is made to the
accompanying drawings and detailed description and its scope will
be pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram representation of an embodiment
of the system of these teachings;
FIG. 2 is a graphical schematic representation of an embodiment of
a component of the system of these teachings;
FIG. 3 is a graphical schematic representation of another
embodiment of a component of the system of these teachings;
FIGS. 4a, 4b are graphical schematic representations of yet other
embodiments of a component of the system of these teachings;
FIG. 4c is an example of a typical amplitude response of a
shell-type resonator across a 3 MHz frequency span.
FIGS. 5a, 5b are graphical schematic representations of further
embodiments of a component of the system of these teachings;
FIG. 6 is a graphical schematic presentation of a yet further
embodiment of a component of the system of these teachings;
FIG. 7 is a graphical schematic representation of still a further
embodiment of another component of the system of these
teachings;
FIG. 8 is a graphical schematic representation of yet another
embodiment of a component of the system of these teachings;
FIG. 9 is a graphical schematic representation of an embodiment of
another component of the system of these teachings
FIG. 10 is a graphical schematic representation of another
embodiment of another component of the system of these
teachings;
FIGS. 11a, 11b are graphical schematic representation of other
embodiments of another component of the system of these
teachings;
FIG. 12 is a graphical schematic representation of an embodiment of
a further component of the system of these teachings; and
FIG. 13 represents a schematic flowchart representation of an
embodiment of the method of these teachings.
DETAILED DESCRIPTION
In one instance, sufficiently (also referred to as substantially)
unique characteristic signals may be generated by micromechanical
resonator structures when such structures are excited. Sufficiently
unique refers to signals that are of sufficient uniqueness that
there are enough of them to uniquely identify each object within a
class of objects by association of a particular signal with each
object in that class. Substantially (sufficiently) unique
characteristic signals are such that regeneration or reassignment
of an existing unique signal to another object within the class is
highly unlikely or effectively impossible. The structures may have
a unique characteristic signal due to their design and
configuration in combination with limitations inherent in physical
creation of such structures. Once constructed, a sample
characteristic response signal of one or more resonator structures
may be obtained and stored. The stored sample may be used
thereafter with a degree of confidence to identify that resonator
structure. For example, if the micromechanical resonator structure
is attached or included in an object, the object may be identified.
The disclosed technology thus may be used to identify and/or
authenticate an object, and in turn, a person associated with such
an object.
Applications that may benefit from such a sufficiently unique
characteristic signal include, but are not limited to, applications
that currently use RFID tags, such as proximity identification
cards, credit cards, product identification, document
identification, security systems, computer authentication systems,
physical authentication systems, as well as other applications.
FIG. 1 depicts a schematic block diagram representation of an
embodiment of a system according to an aspect of these teachings.
Referring to FIG. 1, a micromechanical resonator structure 20 is
subjected to excitation from an excitation subsystem 30. The
excitation subsystem 30 is capable of exciting motion of the
micromechanical resonator structure 20. The micromechanical
resonator structure 20 is connectively positioned with respect to
an object (not shown). The object may be any suitable thing,
constructed out of any material, that may include, for example, but
is not limited to, a solid, fluid, gel, liquid, textile or fabric,
and/or some combination. The micromechanical resonator structure 20
may be connectively positioned in any suitable manner, including,
but not limited to, being disposed on the object, being disposed on
a substrate and the substrate affixed to the object, being
intermixed with the object, being inter-textured with the object,
and/or some combination. For example, a micromechanical resonator
structure 20 may be implemented on a substrate, for example, and
the substrate embedded in or mounted on an object such as a card.
As another example, the object may be a liquid, and a substrate on
which a micromechanical resonator structure 20 is implemented may
be suspended in the liquid.
The micromechanical resonator structure 20 has a characteristic
signal that is sufficiently unique (one of a kind) such that it may
be distinguished from other signals with a degree of confidence.
The characteristic signal may be determined by measurement
performed by one or more of a variety of techniques. A detection
subsystem 40 is capable of detecting such a characteristic signal
45 when motion of the micromechanical resonator structure 20 is
excited. For example, the characteristic signal 45 can include, but
is not limited to, a vibration spectrum or a spectrum of the
induced motion or phase as a function of frequency for the induced
motion or phase of response with respect to the detection subsystem
and/or some combination. For example, the relative amplitude,
quality factor and/or phase of a single- or multi-molded resonant
spectrum may be detected.
An analysis subsystem 50 compares the detected characteristic
signal to a previously determined characteristic signal. If the
detected characteristic signal is sufficiently similar to the
previously determined characteristic signal, the object
connectively positioned with respect to the micromechanical
resonator 20 may be identified and/or authenticated.
FIGS. 2, 3, 4a, 4b and 5a-5b show various embodiments of excitation
subsystems, such as the excitation subsystem 30. FIGS. 6 and 7 show
embodiments of a detection subsystem. FIGS. 9, 10 and 11a, 11b
depict embodiments of micromechanical resonator structures, such as
the micromechanical resonator structure 20.
A shell type micromechanical resonator structure is shown in FIG.
9. In one instance, the shell type micromechanical structure is
constructed by fabricating a thin-film membrane over a gap. One
means of fabricating such a thin-film membrane, but not the only
means, is to begin with a suitable substrate, such as silicon, and
grow, deposit, or otherwise obtain upon the silicon substrate a
sacrificial film of material such as silicon dioxide. Subsequent to
obtaining a sacrificial film upon the substrate, a film of material
from which the thin-film membrane will ultimately be created, is
grown, deposited, or otherwise placed upon the sacrificial layer.
This film that will contain the device is commonly referred to as
the device-layer of material. Common device-layer films include,
but are not limited to, silicon, silicon nitride, and polysilicon.
The device-layer is patterned in such a way as to create the
thin-film membrane device upon removal of the sacrificial layer.
One means of patterning the device layer is to mask the device
layer with photoresist, perform photolithography, remove the
exposed photoresist, and finally reactive ion etch away portions of
the device layer. Another method of patterning the device-layer
would be to use electron-beam resist and pattern the electron-beam
resist with an electron beam. Reactive ion etching would then be
used to remove portions of the device layer. These two methods are
not exclusive of other methods that can be used to pattern the
device layer, and other methods include, but are not limited to,
ion milling the device layer or using biological samples such as
self-assembled s-layer proteins as a mask. The exposed sacrificial
layer is typically removed by means of isotropic etching.
Typically, but not exclusively, this is performed with hydrofluoric
acid. When a suitable amount of sacrificial material is removed
from beneath the device layer, the etch is stopped and the
thin-film membrane is created. Technical papers describing this
process in detail can be referenced: Zalalutdinov et al., Applied
Physics Letters, Vol. 83, pp. 3815-3817. 2003; also, Zalalutdinov
et al., Applied Physics Letters, Vol. 78, pp. 3142-3144. 2001. Note
that this latter reference describes a structure different from
that shown in FIG. 9, but for which the fabrication process is
similar and the device has a unique characteristic signal typical
of that described in these teachings. This latter device is
commonly referred to as a mushroom-type resonator, or a
center-clamped plate resonator, or as simply a suspended plate
resonator.
A string type micromechanical resonator structure is shown in FIG.
10. In one instance, the string type micromechanical resonator is
fabricated utilizing photolithography tools. (See for instance,
Verbridge et al., J. App. Physics, High-quality factor resonance at
room temperature with nanostrings under high tensile stress, volume
99, 124304, 2006, which is incorporated by reference herein.) A
string-type micromechanical resonator structure is shown in FIG.
10. In one instance, the string type micromechanical resonator is
fabricated using non-lithographic techniques. This method is
described in, for example, Verbridge et al., Journal of Applied
Physics, Vol. 99, 124304, 2006. In the method described in the
paper, poly methyl methacrylate) (PMMA) is deposited onto a device
layer of material using electrospinning. Micro- and nano-scale
structures are achievable using electrospinning. The PMMA is
subsequently used as a mask layer for patterning of the device
layer. Once the device layer is patterned using, for example,
reactive ion etching, a sacrificial layer below the device layer is
removed, for example, with isotropic etching.
Other methods for making string-type micromechanical resonators are
also commonly used. For example, the methods described with respect
to FIG. 9 can be used to fabricate string-type resonators,
Photolithography or electron-beam lithography can be used to
pattern resist on a device layer. Such a process is described in,
for example, Carr & Craighead, Journal of Vacuum Science and
Technology B, Vol. 15(6), 2760-2763 (1997). As described above, the
patterned device layer is suspended in subsequent fabrication steps
by removal of a sacrificial layer of material upon which the device
layer rests. Upon removal of the sacrificial layer, the device is
freely suspended and can resonate.
Shell-type or dome resonator structures, string or double-clamped
beam resonating structures, mushroom or suspended plate resonating
structures, and cantilever structures have been described as
resonators that may be used in micromechanical resonator
structures. It should be understood that these structures are not
exclusive of the types of micromechanical (which may include
nano-mechanical) structures that also may be used, instead, in
addition or in combination. For example, bridge resonators, slit
resonators, ring resonators, disc resonators, wine-glass
resonators, plate resonators and tuning fork resonators are
non-limiting examples of structures that may be used.
It is also possible to fabricate coupled arrays of resonators. Such
a structure is shown in FIG. 11a (from Zalalutdinov et al., Applied
Physics Letters, Vol 88, 143504, 2006, which is incorporated by
reference herein.). The structure in FIG. 11a is a two-dimensional
coupled array, though one-dimensional coupled arrays are also
possessive of the unique resonance properties described throughout
these teachings. The structure in FIG. 11a, which is indicative of,
but not an exclusive example of, such a two-dimensional coupled
array, is fabricated using an SOI wafer and techniques similar to
those described with respect to FIG. 9. Electron-beam resist and
lithography may be used to pattern the device layer, and subsequent
isotropic etching removes the sacrificial layer, releasing the
resonator devices. A two-dimensional coupled array is one in which
each resonator is mechanically coupled to other resonators. Such
coupling is typically achieved through device-layer interconnects
(such as those shown in FIG. 11a, which are thin beams in the
device layer), though other means of coupling can be used,
including coupling of the motion of one resonator to the others
through the substrate. One important feature of a coupled array of
resonators, and a feature not exclusive to two-dimensional coupled
arrays, is that, because of the coupling of resonators, the
response of the array to excitation is a strongly-dependent
function of the conditions of the entire array. For example,
exciting the array in one particular portion of the array is likely
to produce a response significantly different than the response
obtained by exciting a different portion of the array. Response is
taken to include the frequency response, the amplitude at each
frequency of the response, and the phase response, but is not
exclusive to these only. Additionally, it is not necessary for the
coupled array of resonators to exhibit different responses when
excited in different positions or by different means.
A 2-dimensional array of cantilever beam type micromechanical
resonators is shown in FIG. 11b. In the array shown in FIG. 11b,
the characteristic signal corresponding to excited motion of the
array is substantially a combination of the characteristic signals
of each micromechanical resonator in the array structure.
In one instance, the characteristic signal, such as, but not
limited to, the frequency spectrum and/or the phase versus
frequency characteristic, of each micromechanical resonator is
constructed to be substantially unique due to the high Q (referred
to also as the quality factor) of the resonator behavior and small
imperfections resulting from microfabrication variations. The small
imperfections induced by microfabrication variations (typical of
any fabrication process but accentuated by the small size of the
features) detectably alter the characteristic signal. Fabrication
variations are an unavoidable consequence of micro- and
nanofabrication techniques. The variations are caused both by
random, atomic-level variation in processes such as, but not
exclusive to, reactive ion etching, thin-film growth, and isotropic
etching, as well as by resolution limits of lithography tools such
as, but not limited to, photolithography tools, ion mills, and
electron beam lithography tools. Even state-of-the-art tools
exhibit atomic level fabrication variability, and all
state-of-the-art tools will always exhibit such variability unless
those tools involve the individual positioning of every atom
comprising the resonator structure. It is noteworthy that in many
applications, such as but not limited to microelectromechanical
systems for accelerometers, such fabrication variability is
undesirable and significant time and resources are devoted to
attempting to reduce such variability. While often not desirable in
other applications, microfabrication variations are a benefit in
this context, because they make it difficult to deliberately
duplicate a micromechanical resonator structure, and the resulting
characteristic signal produced by that micromechanical resonator
structure.
For example, for resonators with quality (Q) factors between 10,000
and 50,000, it is possible to identify shifts of less than 1 kHz
from the center frequency. If imperfections due to manufacturing a
10 MHz resonator may result in no less than a +/-3% frequency
error, which is typical, there are approximately 600 different
detectable values for that resonator, which value will be randomly
established during manufacturing process by fabrication-induced
variations.
As one non-limiting example, a micromechanical resonant structure
with six modes could exhibit more than 10.sup.14 possible
combinations of resolvable mode frequencies. In this example, each
mode is assumed to have a resonant frequency near 10 MHz and have a
quality factor of approximately 10,000. These values of typical of
commonly fabricated micro- and nanomechanical resonators. Given a
typical variability of the resonant frequency of about +/-1.5%,
there are then 300 different, resolvable frequencies for one such
resonant mode. Given that the example uses six resonant modes,
assumed to have equal variability and nominal resonance frequencies
near 10 MHz, then the number of possible combinations of
identifying signals, taken as the superposition of the six
resonance frequencies, is 300*299*298*297*296*295, which is
.about.10.sup.14.
Here, a mode is a particular resonant mode of the resonator. For
example, a string resonator has modes corresponding to harmonic
multiples of the fundamental frequency. Other types of resonators
have modes having frequencies that are multiples of the fundamental
mode in addition to modes having frequencies that are not related
to the frequency of the fundamental mode. Some of these modes have
frequencies that are relatively closely spaced in frequency space,
so that, for example, within a 3 MHz frequency window on a
detector, the frequencies resulting from multiple excited modes
might be detectable. FIG. 4c is an example of just such a detection
window, which is wide enough in frequency space to observe the
frequencies of eight distinct resonance modes of a shell-type
resonator. FIG. 4c is taken from Zalalutdinov et al. Applied
Physics Letters, Vol. 83(18), 3815-3817, 2003.
For an array of such micromechanical resonators, the number of
possible combinations of frequencies in the spectrum can be greater
than 10.sup.60. The large number of possible choices of
characteristic signal results in a characteristic signal that is
substantially unique.
An embodiment of the excitation subsystem 30 is shown in FIG. 2.
(In one embodiment, the excited motion comprises frequencies within
a frequency range of the sufficiently unique previously determined
characteristic signal.) In the embodiment of an excitation
subsystem 30 shown in FIG. 2, a heating component 70 induces
thermal heating and thermal stresses in the micromechanical
resonator structure 60. The heating component may be local, and
provided in the same substrate, or in the same device or object, as
the micromechanical resonator structure 60, and/or the heading
component may be provided externally, such as part of a exciter.
Any suitable heating component 70 may be used. As a non-limiting
example, a laser is used as a heating element. As another example,
an infrared-emitting diode may be used. Typical powers used to
thermally excite resonators are on the order of microwatts.
Depending upon the exact excitation mechanism, the efficiency of
the coupling between the excitation mechanism and the resonator,
and the thermal properties of the resonator itself, such powers
would typically induce local temperature changes in the resonator
on the order of 1 degree Kelvin. Such temperature changes within
local areas of the resonator material result in local stress which
leads to local deformation of the resonator on the order of
nanometers (or less), which is the source of the resonant motion.
The aforementioned values are typical of devices described in the
following papers, Aubin et al. Journal of Microelectromechanical
Systems, Vol. 13(6), pp. 18-1026, 2004; and Reichenbach et al. IEEE
Electron Device Letters, Vol. 27(10), pp. 805-807, 2006; but it
should be understood that the values needed may be different
depending on the type of excitation used, structure selected, and
the particular configuration.
Referring to FIG. 3, in various embodiments, a local heating
component can be a patterned resistive region, such as region 85 on
micromechanical resonator structure 80, that is proximate to the
micromechanical resonator structure 80. Such a patterned resistive
region may generate heat when energized. Thus, a circuit may be
configured to receive radiant energy (e.g., from an energizing
signal) and energize to such a resistive region to generate heat.
Such a circuit also may be powered by a battery, power line, or
other power source.
In another embodiment, shown in FIG. 4a, the micromechanical
resonator structure 80 may be configured such that motion is
induced by the Lorentz force (the orthogonal force acting on a
charged particle traveling in an electric field). The
micromechanical resonator structure 80 may for example be placed in
a magnetic field, produced by source of magnetic field 90, and has
an electrical conductor 85 associated with it that has a current
induced within it by an excitation signal, so that the conductor
experiences a force that is transferred to the micromechanical
resonator structure 80, which will in turn vibrate. A typical
magnetic field that would be used to excite a resonator in such a
configuration as described above is on the order of 1-7T. See, for
example, Cleland & Roukes, Applied Physics Letters, Vol.
69(18), pp. 2653-2655, 1996.
The magnetic field may be provided, e.g. by a permanent or
electromagnet on or near the substrate or, during reading, by an
external field applied at the same time as an excitation signal to
supply the current i.sub.ac. The current in the conductor may be
induced through an associated antenna, e.g. a coil that couples the
excitation signal to the electrical conductor 85, and the same
circuit may be used to detect a change in impedance when the
micromechanical resonator structure vibrates.
In one embodiment, shown in FIG. 5b, motion of the micromechanical
resonator structure 80 is induced by an electrostatic force. For
example, a charged micromechanical resonator structure may move
under an electrostatic attractive and/or repulsive force with one
or more electrodes. In one instance, the micromechanical resonator
structure 80 is provided with an electrode thereon that couples
capacitively with a further electrode. The two electrodes may
connect with an electric circuit for supplying an ac current
thereacross. When the ac current has frequencies that correspond to
frequencies in the characteristic signal of the micromechanical
resonator structure 80, the micromechanical resonator structure 80
may be strongly excited. The ac frequency used to excite motion in
the resonator can be the fundamental resonance frequency of the
resonator, or can be any multiple or fraction of the resonance
frequency of the resonator.
In one embodiment, shown in FIG. 6, motion of the micromechanical
resonator structure 140 is induced by a piezoelectric force. For
example, the micromechanical resonator structure 140 may have a
piezoelectric material 150 provided thereon, with electrodes on
opposing sides of the material that connect with a circuit for
supplying an ac current thereacross. When a current is applied to
the piezoelectric material, the material will strain, e.g. expand
and contract, and will cause the resonant member to deflect
upwardly or downwardly.
The micromechanical resonator structure 140 may include one or more
layers of piezoelectric material 150, and in one embodiment, the
micromechanical resonator structure 140 includes a pair of
piezoelectric layers arranged to deflect in opposite directions,
e.g. by having their polarization directions pointing in opposite
directions or by applying the current to each layer in opposing
polarities. The use of piezoelectric layers is an exemplary
embodiment of exciting motion of the micromechanical resonator
structure by coupling motion from another structure.
In one embodiment, shown in FIGS. 4b and 5a, the micromechanical
resonator structure 110 may include one or more layers of
conductive material 120 and the one or more layers of conductive
material 120 may be electrically connected to ground. The
micromechanical resonator structure 110 is exposed to an
electromagnetic field from a source 130. (The electromagnetic field
source can be connected directly to the conductive layer 120, as in
FIG. 5a or can be a radiating source as in FIG. 4b.) The one or
more layers of conductive material 120 can include a piezoresistive
layer. In some instances in which the one or more layers of
conductive material 120 include a piezoresistive layer, the
excitation of the motion may include both electromagnetic forces
exciting the micromechanical resonator structure and induced
stresses in the micromechanical resonator structure. Since a
quasi-static magnetic or electric field is an electromagnetic
field, excitation by magnetic fields and quasi-electrostatic fields
are examples of exciting the micromechanical resonator structure
electromagnetically.
Another way to electromagnetically excite the micromechanical
resonator structure includes exciting surface plasmons on one or
more layers of conductive material 120. In some such embodiments,
in which surface plasmons are excited on one or more layers of
conductive material deposited or disposed on the micromechanical
resonator structure, the one or more layers of conductive material
are connected to an external circuit or ground.
In some embodiments, the micromechanical resonator structure 110 is
excited by impinging acoustic waves. If the source 130 in FIG. 4b
is replaced by a source of acoustic waves, the acoustic waves may
excite motion of the micromechanical resonator structure 110. The
one or more layers of other material 120 are not required if
acoustic waves are used as the excitation.
Since many of the excitation systems are substantially linear and
reciprocity applies, techniques applied for excitation also may be
applied for detection. For example, in the embodiment shown in FIG.
7, the device 160 is a light source (where a light source may
provide electromagnetic radiation over frequencies other than in
the visible frequency range), such as, for example, a laser,
utilized to optically detect the characteristic signal by
reflecting and/or scattering the radiation from the light source
160 by the micromechanical resonator structure 20. A detector 170
receives the reflected/scattered radiation. The embodiment shown in
FIG. 7 is an exemplary embodiment of a displacement detection
subsystem. The embodiments shown in FIGS. 3 through 6, for example,
also can be applied to electromagnetically detecting the
characteristic signal.
In an embodiment shown in FIG. 8, a component 180 that senses a
change in impedance (such as, but not limited to, one plate of a
capacitor, where the micro mechanical resonator structure 20 is the
other plate of the capacitor or a proximity sensor sensing a change
in inductance, for example, where the micromechanical resonator
structure 20 has a region of deposited magnetic material) is
utilized to detect motion of the micromechanical resonator
structure 20.
In the embodiment shown in FIG. 8, a component 180 that senses a
change in impedance (such as, but not limited to, one plate of a
capacitor, where the micromechanical resonator structure 20 is the
other plate of the capacitor or a proximity sensor sensing a change
in inductance, where the micromechanical resonator structure 20 has
a region of deposited magnetic material) is utilized to detect
motion of the micromechanical resonator structure 20.
In a variation of the embodiment shown in FIG. 8, the component 180
conducts a current as a result of electromagnetic interactions
between the resonator and the substrate (the top and bottom plates
of a capacitor-like structure, respectively). The induced current
may be directed to another circuit through electrical connections
and detected as a direct result of motion of the resonator. The
induced current also may be measured directly as a means of
detecting the motion of the resonator. Alternatively or in addition
to the aforementioned measurements, the induced current may be
converted into a voltage, for example by a transresistance
amplifier, resistor, or other means of transducing voltage from
current.
The detected signal obtained in the detection subsystem 40 of FIG.
1 is analyzed in order to obtain the characteristic signal. A
component (175, FIG. 8), such as, but not limited to, a spectrum
analyzer, an interferometric system, and/or a spectrophotometer, is
used in order to obtain the characteristic signal. In one
embodiment, the characteristic signal is the frequency spectrum (in
one instance, the amplitude as a function of frequency). In another
embodiment the characteristic signal is the phase as a function of
frequency. The characteristic signal may be some combination of
these or other suitable signals.
The characteristic signal obtained from the detection subsystem 40
may be compared to a previously determined characteristic signal by
an analysis subsystem 50. In some embodiments, an example of which
is shown in FIG. 12, the analysis subsystem 50 includes one or more
processors 210 and one or more computer usable media 230 having
computer readable code embodied therein, the computer readable code
being capable of causing the one or more processors 210 to receive
the detected characteristic signal from the detection subsystem,
compare the received detected characteristic signal to the
previously determined characteristic signal, and identify and/or
authenticate if said received detected characteristic signal is
sufficiently similar to said previously determined characteristic
signal. The analysis subsystem, in an embodiment such as shown in
FIG. 12, can also include another computer readable medium 240
having the predetermined substantially unique characteristic signal
stored therein. This may include measurements of the signal and/or
data derived from measurements of the signal, such as using signal
processing and/or cryptographic techniques. Referring to FIG. 12,
the one or more processors 210, the one or more computer usable
media 230 and the other computer usable media 240 are operatively
connected by means of a connection component 225 (such as, but not
limited to, a computer bus).
Referring to FIG. 13, during operation of various embodiments of a
system, a micromechanical resonator structure 20 is connectively
positioned with respect to an object (step 310, FIG. 13). Again,
the object may be or may include any type of matter or material,
including without limitation a solid, liquid, gel, plasma, and so
on. Motion of the micromechanical resonator structure is excited
(step 320, FIG. 13), a characteristic signal of the excited motion
is detected (step 330, FIG. 13) and compared to a previously
determined characteristic signal (steps 340, FIG. 13). The object
can be identified and/or authenticated as a result of the
comparison (step 350, FIG. 13).
In some embodiments, the characteristic signal (also referred to as
features of a specific excitation response) may be determined
before the micromechanical resonator structure is connectively
positioned with respect to the object. For example, the
micromechanical resonator may be positioned on a substrate. The
specific excitation response is determined by exciting the
micromechanical resonator and then detecting the features of the
specific excitation response signal (steps 320, 330, FIG. 13). The
detected features are stored as stored comparison signal features.
The substrate then is attached to the object. The micromechanical
resonator is excited and features of the response signal obtained
from the excitation are detected and compared to the stored
comparison signal features.
In many embodiments, micro- or nanomechanical resonator structures
are excited with amplitudes of motion such that their total
displacement from their stationary position is small. This is
referred to as linear drive, linear motion, or linear response of
the resonator. It should be recognized, however, that non-linear
actuation is also possible and is potentially useful for achieving
further unique signals from resonator devices. In many instances, a
resonator structure, excited by any means, may be driven
non-linearly. Resonators are typically made to oscillate
non-linearly by driving them with large ac drive signals. The text
of these teachings, particularly sections referring to driving or
exciting resonators, may include driving or exciting resonators
such that the resulting motion is non-linear. Detection of
non-linear motion is performed in a similar manner as the detection
of linear motion. Non-linear excitation of resonators and
subsequent detection of non-linear resonance may be used to
distinguish actual micromechanical resonators from otherwise
fraudulent frequency sources that might otherwise be used in an
attempt to fool, trick, or otherwise confuse a detection device,
for example, in an attempt to impersonate or otherwise fraudulently
authenticate an object or person. As difficult as it might be to
construct a device that could emulate the characteristic signal of
a micromechanical resonator structure under linear excitation, it
is significantly more difficult to simulate the response to
non-linear excitation.
One embodiment of a unique signal for identification or
authentication that can be obtained from micro- or nanomechanical
resonators is the amplitude response as a function of frequency.
This response is typically, but not exclusively, detected by means
of transduction of a voltage in response to the resonant motion.
These detection techniques have been described herein above.
Another measurable response of the resonator motion is the phase of
the resonator response with respect to the actuation. Detection of
the phase of the resonator response also facilitates uniquely
identifying or authenticating resonators or the objects to which
resonators are attached. Furthermore, it is also possible to
include the phase response of a resonator with the amplitude and
frequency response of a resonator or array of resonators, either
coupled or independent, when associating a particular unique
response with a resonator and with an object to which a resonator
is attached.
Parametric amplification of the response of a resonator or an array
of resonators is also a technique for driving and detecting a
resonator or an array of resonators. Parametric amplification of
micro- and nanomechanical resonators is described in detail in, for
example, Carr et al. Applied Physics Letters, Vol. 77(10), pp.
1545-1547, 2000; and Zalalutdinov et al. Applied Physics Letters,
Vol. 78(20), pp. 3142-3144, 2001. Parametric amplification in
mechanical resonator systems may include, but is not limited to,
the process of pumping the spring constant of the resonator at
twice the fundamental frequency with a phase offset from the
fundamental driving frequency to achieve either an increase or a
decrease in the amplitude of the response of resonator as compared
with the response when only the fundamental driving frequency is
used to excite the resonator. The width of the frequency response
of the resonator, often characterized by its full width at half the
maximum amplitude, or the quality factor of the resonator, is also
altered when the resonator undergoes parametric amplification. For
example, when the resonator is driven at the fundamental frequency
and twice the fundamental frequency with the double frequency
component being phase offset by 90 degrees, then the amplitude of
the response is typically increased and the width of the response
is narrowed. Parametric amplification is applicable to both
individual resonators and arrays of resonators, either coupled or
not coupled. Parametric amplification may be used to excite and
detect resonator motion so as to increase the degrees of freedom
available in assigning uniqueness to a particular unique resonator
signal. Parametric amplification also may be used to distinguish
identification or authentication by means of a resonator or an
array of resonators from a possible fraudulent frequency source
that is intended to trick, fool, or otherwise confuse a detector
system into regarding the fraudulent frequency source as a valid
identification or authentication source.
Elements and components described herein may be further divided
into additional components or joined together to form fewer
components for performing the same functions.
Each computer program within the scope of the claims below may be
implemented in any programming language, such as assembly language,
machine language, a high-level procedural programming language, or
an object-oriented programming language. The programming language
may be a compiled or interpreted programming language.
Each computer program may be implemented in a computer program
product tangibly embodied in a computer-readable storage device for
execution by a computer processor. Method steps of the invention
may be performed by a computer processor executing a program
tangibly embodied on a computer-readable medium to perform
functions of the invention by operating on input and generating
output.
Common forms of computer-readable media include, for example, a
floppy disk, a flexible disk, hard disk, magnetic tape, or any
other magnetic medium, a CDROM, any other optical medium, punched
cards, paper tape, any other physical medium with patterns of
holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory
chip or cartridge, or any other medium from which a computer can
read. A carrier wave is an equivalent of the above described forms
of computer readable media.
Applications
It should be understood that the techniques described here may be
advantageous in applications in which it is desired that one
resonator structure or numerous resonator structures with different
frequency combinations be produced, and in which each particular
characteristic signal is difficult to reproduce (e.g.,
counterfeit). Exemplary embodiments are described hereinbelow. It
should be noted that these teachings are not limited only to these
exemplary embodiments.
For example, in an implementation in which the frequency spectrum
is the characteristic signal, micromechanical resonators may emit
signals with a very high Q at high frequencies. With current
technology, it is currently technically challenging, expensive, or
not possible to produce such signals with digital electronics, and,
as discussed, manufacturing variation makes it unlikely that a
particular resonator or array of resonators may be constructed on
demand.
RFID Tags.
In some embodiments, a resonator structure is configured such that
it may be communicated with wirelessly, and used in applications in
which a conventional RFID tag is used presently. For example, a
resonator structure may replace some of the digital electronics and
transmitter in a conventional RFID tag. The exciter may be one of
those described above that can operate over a distance. The
micromechanical resonator structure may be connected to an antenna
and/or other circuit to receive power from the exciter signal to
initiate a response from the micromechanical resonator structure.
The characteristic signal is of sufficient strength, or can be
amplified to a sufficient strength, that it may be received with a
wireless receiver.
Such a micromechanical resonator structure RFID device provides the
characteristic signal as an identifier. A suitable detector may
determine from the characteristic signal which micromechanical
resonator structure RFID device is present and therefore what
associated object (e.g., goods, identification cards, etc.) is
present, with a high degree of confidence. In some cases, the
micromechanical resonator structure may be integrated into a label
or sticker that may be placed on or embedded in an object.
Resonator structures such as those described here also may be used
in combination with conventional RFID technologies. For example, in
some embodiments, an REID tag is constructed on the substrate, or
on the same device, that includes convention RFID components as
well as a micromechanical resonator structure. The RFID tag may be
excited by the same or a different signal than the micromechanical
resonator structure. An RFID tag reader that is so configured may
read the identification number and other information that may be
transmitted by conventional RFID tag components and also may read
the characteristic signal of the micromechanical resonator
structure to further verify the identity with additional
confidence. It is also possible to use an REID tag reader to read
the conventional RFID tag while using a reader specific to exciting
and detecting resonator signals to read the unique resonator
signal. Even though two readers might be used, it is possible that
the identification system would require both the RFID signal and
the resonator signal to be matched in order to generate a valid
response for the tag so interrogated, or the object to which the
tag was attached.
Identification Cards, Documents, and Devices.
A micromechanical resonator structure may be embedded in or mounted
on an identification card, document and/or device, which then may
be used, for example, in systems for entry or exit, to verify the
identity of the card and/or the individual using the card. Various
identification cards, documents, and devices, include without
limitation passports, driver's licenses and other government
identification documents, membership identification cards, and so
on. Each of these types of cards and documents may have a
micromechanical resonator structure embedded or mounted on
them.
In some embodiments, a wireless exciter and receiver, for example,
may be built into a reader, and when the card is brought close to
the reader, the characteristic signal wirelessly read from the
micromechanical resonator structure. The reader may perform the
comparison between the characteristic signal and a previously
determined characteristic signal. For example, the analysis
subsystem such as that of FIG. 13 may be implemented in the reader.
The reader may transmit the characteristic signal to another
device, such as a computer, to analyze the characteristic signal.
For example, an analysis subsystem such as that of FIG. 13 may be
implemented in a device other than the reader that is connected to
the reader.
In some embodiments, one or both of the exciter and receiver may be
temporarily connected to the micromechanical resonator structure
through use of wires or other non-wireless signal propagation
means. Connectors may be provided on the card, document, or device
to facilitate communication between the exciter and/or receiver and
the micromechanical resonator structure.
Identification devices that may include micromechanical resonator
structures are not limited to cards and documents, and may include
any sort of token, machine, or device. For example, a
micromechanical resonator structure may be included in a device
that is roughly key-shaped, such as a house key and/or a
cylindrical bolt-shaped key. Inserting the key into an electronic
lock may facilitate wireless or wired connection between the
micromechanical resonator structure and an exciter, power supply,
and/or receiver. It should be understood that a key shape is not a
limitation, and any suitable shape that allows a micromechanical
resonator structure to be connected to or in communication with an
exciter, detector, and/or power supply may be used.
For example, devices may be used as a key for entry into physical
locations, such as cabinets, closets, room and building entrances,
and so on, for example by actuating an actual lock (e.g., door
lock, electronic lock, padlock, vehicle lock), for access to and/or
operating equipment (e.g., vehicles, motorcycles, scooters), and
also for access to any sort of computer-based, communications, or
other restricted items or resources.
Credit, Payment, and Financial Services Cards.
A micromechanical resonator structure may be embedded in or mounted
on a credit card, payment card and/or a financial services card.
For example, in one embodiment, a person provides a card to a shop
clerk, who places the card in a card reader. The card reader
includes an exciter, a detector, and/or power supply for the
micromechanical resonator structure. The micromechanical resonator
structure may interact wirelessly and/or connectedly with the
exciter, detector and/or power supply. The card reader may receive
the characteristic signal, and use it to verify the authenticity of
the card, by matching the received signal with information on the
card, and/or by providing the signal (or information derived from
the signal) to an analysis subsystem, which compares the received
characteristic signal to a previously determined signal. The
analysis subsystem may be on the shop premises and/or in
communication with the shop premises by a telephone network, data
network, and so forth.
Product and Item Authentication.
A micromechanical resonator structure may be embedded in or mounted
on a product. For example, the micromechanical resonator structure
may be provided on a label that is attached to a pallet, box,
container, product packaging bottle, and so forth. A reader may be
portable or stationary, and may contain an exciter, detector and/or
power supply for the micromechanical resonator structure. The
reader may operate wireless or connectedly with the micromechanical
resonator structure. A person with a reader can use the reader to
identify, or verify the identity of the products.
For example, a pharmaceutical company may provide a container that
includes a substrate with a micromechanical resonator stricture. A
pharmacist may check the authenticity of the package before
distributing the pharmaceuticals to patients.
As another example, a machine with disposable and/or
interchangeable components may include a reader that interacts with
a micromechanical resonator structure in order to determine whether
the parts that are installed in the machine are the correct parts,
or are parts from the manufacturer of the equipment.
Similarly, collectables (e.g., baseball cards, artwork, toys, and
so on) and/or valuables (e.g., jewelry, gemstones), may be enclosed
in a container with, or have affixed to them, a micromechanical
resonator structure, which may be used to identify the items and/or
the authenticity of the items.
Suspended, Interwoven, and Printed a Applications.
In any or all of the abovementioned applications, it may be
necessary or desirable to suspend substrates containing RFID tags
and micromechanical resonators capable of receiving a signal and
sending a signal in a liquid ink, or other liquid-like solution.
The end-application may be identification of the liquid-like
substance itself, as in, for example, identifying blood samples.
Or, the end-application may be in using an ink-like material to
mark a surface and in which one would like to use not only the
marking of the ink but the unique resonator signal of the resonator
suspended and printed with the ink as a means of identifying the
ink and/or the material or object upon which the ink is printed.
For example, identifying documents or currency is possible with
resonator-infused inks that are printed on the documents or the
currency.
Substrates containing unique resonator structures may also be
attached to fibers, stands, or other materials that are commonly
interwoven to form a composite material. The resonator structure so
embedded in the fiber-like material may then be used to identify or
authenticate the composite material. For example, an article of
clothing may be partly or wholly composed of fibers that have
imbedded in them or otherwise attached to them micromechanical
resonator structure capable of receiving and sending unique
signals, thus enabling identification of the article of clothing.
It should be noted that clothing is only an example of a composite
material in which resonator-embedded fibers may be used and should
not be limiting of other applications in which resonator-embedded
fibers may be used to perform identification of the composite
object.
Although the teachings have been described with respect to various
embodiments, it should be realized these teachings are also capable
of a wide variety of further and other embodiments within the
spirit and scope of the appended claims.
* * * * *